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Unlimited data SIMs: The Essential Guide

With so many SIM plans available, it can be difficult to choose the right one for you. One of the hardest things is figuring out how much data you’ll need. In this guide, we explain what unlimited data is, the pros and cons of choosing an unlimited data SIM, and how to know if it’s worth it. 

Last updated: 21st Dec 2020 at 10:37am

What is unlimited data?

Mobile data allows you to access the internet without being connected to Wi-Fi. Devices can use 3G or 4G to get online, with 5G also on the rise around the world. 

Unlimited data means that you don’t have a data cap on your plan, so your ability to use the internet won’t be hindered by a limit - you can use it as much as you need.

Pros of unlimited data SIMs

If you’re a heavy data user, or don’t often have access to Wi-Fi, then an unlimited data SIM is one of the best plans for you. Here are some of the benefits of having no data cap:

Commuting and long journeys will no longer be a bore

If you take public transport to work or travel often, having unlimited data will undoubtedly be helpful for the following tasks:

  • You can stream without worrying about running out of data, be it movies, YouTube videos, music, or online courses 
  • Download, update, and use apps without limit
  • Skype or FaceTime friends and family 
  • Excessively use travel apps to get the most out of trips
  • Update anything without the need to connect to a router

With unlimited data, you don’t necessarily have to rely on paid services (like some public transport Wi-Fi) while travelling, which could save you money.

Save money on utilities

If you choose to invest more of your money in an unlimited data SIM plan, you could skip the cost of installing broadband in your home. Instead, you could use your phone as a hotspot to connect all other devices to (though this can drain your battery more quickly). Not all plans will let you do this, so it’s best to do your research first. 


Unlimited data is also usually quite fast, so you don’t have to compromise on speed or accessibility with this sort of SIM. Sometimes you might find that your mobile data is actually faster than Wi-Fi. If you notice that your phone is struggling when connected to a router, with unlimited you wouldn’t even have to think twice about switching to data. 

Cons of unlimited data SIMs


Unlimited data is naturally more expensive than SIM plans that have data caps on them. You’ll have to consider your monthly budget to make sure it’s affordable.


Unlimited data is really only suitable for people who heavily rely on mobile internet. If you don’t really use data that much, or tend to connect to hotspots and routers when you’re in range, then a plan like this will be a waste and not utilising the full benefits of what you’re paying for.

Fair usage limits

Unlimited data SIMs allow you to use as much data as you wish, subject to fair usage. Though the term ‘unlimited’ does imply limitless access, some contracts may actually have restrictions in terms of how you can use your data. For example, it may not be able to support multiple devices, or your internet access may be compromised after a certain amount of usage.

Speed caps

Not all unlimited data deals come with the same speed, even if from the same provider. You may find that cheaper bundles put a cap on your data speed, even if you can connect to 4G or 5G. Always check the terms and conditions to avoid disappointment. 

How to figure out if you need unlimited data

Not sure if it’s worth the cost or can’t figure out how much data you need? Ask yourself the following questions:

  1. Do you spend a lot of time off Wi-Fi, either privately or in public?
  2. Do you use your phone frequently throughout the day?
  3. Do you consume a lot of varied online content? Like social media, YouTube, Spotify, and e-books
  4. Do you spend a lot of time travelling?
  5. Do you consistently hit your current data cap? If you’re not sure, it’s easy to find out.
  6. Do you find yourself trying not to use your phone outdoors so you don’t reach your data limit?

The more that you answer yes, the more likely you’d benefit from an unlimited data SIM. 

If you know you don’t need unlimited data, but you’re not sure what type of data cap to buy, you can use our bundles calculator

For more information on data usage, check out our guides:


Is unlimited data actually unlimited?

For the most part, unlimited data plans are exactly that - unlimited. However, as mentioned earlier, your contract may include some tethering or usage restrictions depending on the type of plan you’ve opted for. 

To know for certain if you’re going to encounter any problems, check your contract (and the small print!) for any warnings or restrictions. 

Can I use my unlimited data abroad?

You can only use your unlimited data abroad if you’re in a ‘Go Roam’ / ‘Roam Like at Home’ destination and it’s stated on your contract. This may include different data caps for Europe versus the rest of the world. 

Data roaming can result in additional charges though. Now that the UK has left the EU, the safety net of the ‘Roam Like at Home’ law will no longer apply to UK citizens. This means your network provider will be able to charge you for usage in EU states. 

Can I use my phone as a hotspot with unlimited data?

Yes, you can. By setting up a hotspot on your phone, other devices (like smartphones, tablets, and computers) can connect to your data and access the internet. Tethering without concern is only really possible with unlimited data plans, as allowing multiple devices to access the internet via your connection can drain your data fairly quickly. 

If I don’t use it enough, can I change my unlimited data plan?

This entirely depends on your network provider. It’s generally easier to upgrade a plan than downgrade. If you’re locked into a long contract, you may not be able to without paying a fee. 

If you’re on a short-term contract or deal, such as with Asda, you can change your data limit every 30 days.

Make sure you know your rights before signing up to a contract. 

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